The present invention relates to a bulk-recoverable nonwoven fabric, a process for producing the same and a method for recovering the bulk thereof, and more particularly to a bulk-recoverable nonwoven fabric which can be preferably used as a wadding, a base material for a brassiere cup, a base material for a shoulder pad, a filter and the like, a process for producing the same and a method for recovering the bulk thereof.
A bulky nonwoven fabric containing a large amount of air is generally used as a wadding for clothing such as sportswear and the like, a filter, and the like. Because the bulky nonwoven fabric contains a large amount of air, carrying or storing the bulky nonwoven fabric is the same as carrying or storing air. Accordingly, there is a disadvantage for cost because a considerable space is necessitated when a large amount of the bulky nonwoven fabric is carried stored in a storehouse. There is also a defect that it is inconvenient to handle the bulky nonwoven fabric when producing clothing and the like because the nonwoven fabric is bulky and soft.
In order to overcome the above defects, a method for recovering the bulk of a bulky nonwoven fabric comprising wrapping the bulky nonwoven fabric with a film, removing air from the bulky nonwoven fabric to diminish the bulk of the bulky nonwoven fabric so that the nonwoven fabric can be easily carried or stored, and recovering the bulk of the nonwoven fabric by blowing hot air into the nonwoven fabric when the nonwoven fabric is used, is proposed in Japanese Examined Patent Publication No. 58086/1985.
However, there are some disadvantages in the above method that the bulk-diminished nonwoven fabric is poor in recoverability to the original shape because the arrangement of the fibers of the bulky nonwoven fabric is influenced, and wrinkles or deformations generate when air is removed from the bulky nonwoven fabric. The method is also extreme in labour effectiveness because two processes of removing air from the nonwoven fabric and recovering the bulk of the nonwoven fabric by applying hot air are necessitated. The above method also has not yet been improved in processability because the nonwoven fabric should be used in a bulky state when clothing and the like are actually produced.
In another method latently crimped fibers are compressed and fixed to each other with a powder resin having a low melting point when a nonwoven fabric is produced and the powder resin having a low melting point is remelted to recover the bulk of the nonwoven fabric by heating the nonwoven fabric to a temperature of about 150.degree. C. and then the nonwoven fabric is cooled to solidify the melted powder resin to give a nonwoven fabric having a novel shape when the nonwoven fabric is actually used, is known to the art.
However, when a wadding is produced in accordance with the above method, the nonwoven fabric is fixed in a compressed state or a deformed state at the time of being subjected to a post processing of the wadding because the powder resin is melted when the wadding is heated. Further, the nonwoven fabric produced by the above method has a defect that the nonwoven fabric is poor in durability when the nonwoven fabric is subjected to dry-cleaning because the powder resin is poor in durability against a solvent as well as poor in thermal resistance, and the bonding of the fibers formed by the powder resin is destroyed. Also, since the fibers of the nonwoven fabric are merely fixed to each other by the powder resin, the nonwoven fabric lacks shape stability when the powder resin is reheated to melt the resin. Accordingly, it is not suitable for using such nonwoven fabric as a wadding. Further, since the bulk of the nonwoven fabric is recovered by heating to a temperature of about 150.degree. C., the influence of the heat on the fibers of the nonwoven fabric cannot be neglected.
The object of the present invention is to provide a bulk-recoverable nonwoven fabric which is excellent in durability after the bulk of the nonwoven fabric is recovered, retains shape stability and processability when clothing and the like are produced and which can reduce the cost of storage, a process for producing the same, and a method for recovering the bulk thereof.